add directory bin

bin/time.doc

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+Setting up time and time zones
+
+There are several things involved in getting time right under Linux:
+
+  - /usr/lib/zoneinfo contains files that define what time zone you
+	are in.  If they are missing, no time zone calculations
+	are done, i.e. your internal clock is assumed to be on
+	local time rather than the Unix standard of GMT.  The only
+	file that you absolutely need is /usr/lib/zoneinfo/localtime, but I
+	recommend also having /usr/lib/zoneinfo/posixrules.  Posixrules
+	is typically a copy of or link to localtime.  Localtime defines
+	your default zone.  Posixrules is needed to interpret the TZ 
+	variable, which is used if you want to specify a zone other than 
+	the default.
+
+  - the "date" command can be used to set or display the date/time.
+	Note however that it does not set the hardware clock, so
+	next time you reboot, you'll be back to the old time.
+	I recommend that after changing the time with "date", you
+	use "clock -w" or "clock -u -w" to update the hardware clock
+	as well.  (See below.)
+
+  - the "clock" command can be used to set or display the date/time
+	in the hardware (CMOS) clock.  Typically your /etc/rc script
+	will contain
+		clock -s
+	which will cause the Unix date/time to be initialized from the 
+	CMOS clock when you boot.  If your CMOS clock is set to GMT
+	(which is what I recommend) the correct command is
+		clock -u -s
+
+The binary time distribution should be untarred under /usr.  It
+contains lib/zoneinfo, bin/date, bin/clock, and doc/time.doc (this
+file).  Once you've installed these files, you'll want to do four
+things:
+
+1) set /usr/lib/zoneinfo/localtime and /usr/lib/zoneinfo/posixrules.
+You should copy the file for your time zone.  E.g. if you are in the
+U.S.  Eastern time zone, do
+
+   cd /usr/lib/zoneinfo
+   cp US/Eastern localtime
+   ln localtime posixrules
+
+Localtime defines the local time zone.  Posixrules defines the zone to
+be used to interpret the TZ environment variable.  Since it's far more
+convenient simply to use the right time zone file, nothing more will
+be said here about how the TZ variable is used.  Unless you intend to
+use TZ, you can ignore the next paragraph.
+
+If you want exact POSIX behavior, posixrules should be a copy of or
+link to one of the U.S. time zone files.  (For non-U.S. daylight
+rules, the TZ variable defines the daylight transition rules.)
+However it may make more sense practically for it to be the same as
+localtime, as shown in the instructions above.
+
+2) Once you've set up localtime and posixrules, you can remove the
+rest of the files in /usr/lib/zoneinfo, if you're sure you'll never
+want to operate in any other time zone.  Or you can keep just the few
+time zones that you might need.
+
+3) Put the correct "clock" command into /etc/rc.  Which command to use
+depends upon whether you want your hardware clock to keep local time
+or GMT.  I recommend using GMT, since that will allow daylight savings
+transitions to be completely automatic.  However the same clock is
+used by DOS, and some people don't like the time in DOS being GMT.  I
+use Unix-compatible software under DOS.  It uses the TZ environment
+variable to do time zone conversion.  Thus I prefer the clock being
+GMT even under DOS.  But some people may not like that.  Anyway, if
+your hardware clock is set to the local time, put the line
+
+   clock -s
+
+in /etc/rc.  This will set the Unix time from your hardware clock,
+doing the necessary time conversion.  If your hardware clock is set 
+to GMT, then you'll need the -u option:
+
+   clock -u -s
+
+4) Now make sure that your hardware clock is set correctly.  Try
+"clock" with no arguments.  It will print the current setting of the
+hardware clock.  Make sure it is right, and that it is either local or
+GMT, as you decided.  (If the hardware clock is supposed to be GMT,
+you can use "clock -u".  This will convert from GMT to local and
+display it.)  To set the clock, first use the "date" command to get
+the date right in Unix.  Then use "clock -w" to set the hardware
+clock.  Note that "clock -w" will set the hardware clock to the local
+time, and "clock -u -w" will set it to GMT.  Verify with "clock" that
+the hardware clock is as you want it.
+
+From now on, the time should be right.  If your hardware clock loses
+or gains time, you can update it at a future date by the same
+procedure just described: first get the Unix time right using "date"
+and then use "clock -w" or "clock -u -w" to set the hardware clock.
+
+If your hardware clock is set using local time, make sure to reset it
+when daylight time changes.  If you're running Unix when daylight time
+changes, the Unix time will adjust automatically.  In that case, all
+you need is "clock -w" to update the hardware clock.  If you aren't
+running Unix during the transition, then your time will be an hour off
+the next time you boot.  In that case, set the correct Unix time using
+"date", and then use "clock -w" to update the hardware clock.  If your
+hardware clock is set using GMT time, none of this is necessary --
+daylight time transitions will happen automatically.